The present invention relates to electromechanical switching devices, and more particularly, to a miniature relay in which contacts are opened and/or closed by the dimensional change in a piezoelectric material subjected to an electrical signal.
In general, a relay is an electromechanical device in which contacts are opened and/or closed by variations in the conditions of one electric circuit to thereby affect the operation of other devices in the same or other electric circuits. A relay can be considered to be a form of an amplifier, since a small amount of power to its input can control a much higher amount of power at its contacts. Multiple contact arrangements permit complex control and sequencing actions. One of the most important qualities of a relay is that it enables a high degree of isolation between its control input and its output.
In recent years, solid-state non-mechanical switching devices have come into wide use and their applications are extending rapidly. Nevertheless, relays are still used in large quantities in industrial controls, despite the fact that they have moving part, erodible contacts and relatively slow operation speeds compared to solid state switching devices.
A typical relay has a pivotally mounted armature having a first set of electrical contacts at one end. The other end of the armature is moved by a magnetic force produced by applying an electrical current to a coil wrapped around an iron core. A second set of contacts is mounted adjacent the first set of contacts so that the first and second sets will connect or disconnect upon either energization or de-energization of the coil. The armature carrying the first set of contacts is spring biased so that the first and second set of contacts are either normally open or normally closed.
Heretofore the structure of conventional relays has not lended itself well to miniaturization. However, because of the advantageous signal integrity and isolation capabilities of a relay, it would be desirable to have a miniature relay for use in a wide variety of electronic systems.